The present invention relates to a device for determining the location of a catheter in the bronchi and determining pathological condition in the thorax, and more particularly to a device for determining the position of the distal end, i.e. the tip, of a suction catheter inserted into the bronchi, and for determining pathological condition such as pulmonary edema, pleural effusion, hemothorax, pyothorax, pneumothorax, or neoplasm of the lung.
It is very important for maintaining the life in clinical medicine, particularly in respiratory care of patients under the anesthesia or respiratory insufficiency to remove secretions such as sputum in the bronchi. Removal of secretions is effected by inserting a pliable plastic or rubber suction catheter through either an endotracheal tube or a tracheostomy cannula introduced into the trachea, guiding it into the right or left main bronchus so that the tip is located at the desired position, and sucking the secretions.
In the adult lung, as shown in FIG. 1, the right and left bronchi 2 and 3 which branch off from the lower end of the trachea 1 have different inclinations. The angle .alpha. of the right bronchus 3 to the tracheal axis is about 25.degree. in the average and is smaller than the angle .beta. of the left bronchus 2 which branches off from the trachea 1 at an angle of about 45.degree. in the average. Thus, the tip of the suction catheter inserted through an endotracheal tube or a tracheostomy cannula is easy to enter the right bronchus 3 and is hard to enter the left bronchus 2. Accordingly, the suction of the left bronchus is more difficult than the right bronchus, and the incidence of pulmonary complication on the left lung is higher than on the right lung.
Various techniques and procedures have been attempted and applied to the selective suction of the left bronchus, such as the use of a straight or curved-tip suction catheter, turning the head of patient to the right side and turning the body of patient to the left or right side. However, a definite technique which allows the catheter to selectively introduce into and suck the left bronchus has not yet been established.
A curved-tip catheter is designed so as to be selectively inserted into the desired bronchus with good success. The catheter is inserted through an endotracheal tube or a tracheostomy cannula with the curved-tip directed to the bronchus to be inserted. It is necessary to direct the curved-tip to the bronchus to be inserted during the insertion, but the catheter rotates or twists during the insertion and, therefore, it is difficult to surely insert the tip of the catheter into the desired bronchus.
Also, there is no simple method to determine the location of the tip of catheter, even if the tip enters into the left bronchus. In order to perform the selective bronchial suction, it is necessary to surely determine the position of the tip of the catheter. X-ray monitoring and scintiphotographic technique have been employed for ensuring the positioning of catheter. However, these techniques are not readily available in most situations. In addition, these techniques involve radiation exposure. Bronchoscopy has also been employed when a retained secretion or a foreign body may cause persistent obstruction atelectasis. However, bronchoscopy must be effected by a physician skilled in the technique.
Accordingly, there is desired the development of a device or technique for determining the position of the tip of catheter, which is simple and safe and is usable for anybody at anytime and anywhere. Such a device or technique is of great use for the prevention and treatment of pulmonary complications, for instance, after operations, and greatly contributes to clinical medicine.
On the other hand, auscultation, fluoroscopy, roentgenography, scintiphotography and echography have been used to diagnose pathological condition in the thorax such as pulmonary edema, pleural effusion, hemothorax, pyothorax, pneumothorax or neoplasm of the lung. These techniques are not always safe, simple or easy and readily available except auscultation. Accordingly, there is also desired a development of a method or device which can detect a pathological condition more exactly than auscultation and more safely, simply and easily than fluoroscopy, roentgenography, scintiphotography and echography.